Bee business Wild insects are crucial for crop pollination but they are declining, and their role cannot be compensated for by managed honeybees, say experts.

The comments come in the wake of new findings reported by an international team today in the journal Science.

"We're not saying that honeybees are not important but they are not the be all and end all," says plant ecologist, Dr Margaret Mayfield from the University of Queensland.

"If we want to maximise our food production ... we need to incorporate wild pollinators."

Mayfield says a large proportion of the world's crops rely on insects for production, but removal of native vegetation and use of pesticides kills off many wild insects, which could act as pollinators.

Farmers pay millions of dollars to import hives to do the job but the question is can honeybees do the job of wild pollinators?

They looked at how often flowers were visited by managed honeybees and wild pollinators - including wild bees, butterflies, flies and beetles - and then they looked at how many flowers yielded fruit in each of the crops.

On average wild pollinators increased the fruit yield in all the crops, while honeybees increased the fruit yield in only 14 per cent of the crops.

"I think the going wisdom is that honeybees do everything that we need done so we don't really need to bother with wild insects," says Mayfield.

"This really shows that on average wild insects provide a very substantial service. They're complementary - you need them both."

Interestingly, while the managed honeybees transferred a lot more pollen than the wild pollinators, Mayfield and colleagues found this did not translate into more fruit production.

"A lot of studies tend to use pollen deposition as a proxy for fruit set and you can see why you'd get an overblown view of the importance of honeybees," she says.

Mayfield says there's an ongoing debate over whether we should be growing our crops in a way that allows farmers to take advantage of the "free" ecosystem service of wild pollinators.

Bees knees?

New Zealand ecologist Professor Jason Tylianakis from the University of Canterbury says the importance of pollinators is "hotly argued".

"People up until relatively recently argued that honeybees are as good as wild pollinators if not better," says Tylianakis.

But, he says, this was partly because people were depending on honeybees in areas where wild bees had gone extinct.

In an accompanying commentary in the same issue of Science he argues the latest findings show that managed honeybees cannot compensate for a decline in native honey bees.

He says the new research emphasises the importance of farming in a biodiversity-friendly way.

"It shows biodiversity isn't something we should keep in a box," says Tylianakis. "We need biodiversity on our farms to help with food production."

He says it also highlights the dangers of relying on a single species such as managed honeybees for pollination.

"It likely won't give us the same sort of benefits from having a lot of different species doing the same job," says Tylianakis.